package cn.com.kblog.util;



import java.security.SecureRandom;

import javax.crypto.Cipher;
import javax.crypto.SecretKey;
import javax.crypto.SecretKeyFactory;
import javax.crypto.spec.DESKeySpec;


/**
 * 加密工具类
 * @author KK.Luo
 * Email luokai8@vip.qq.com
 * @date 2013-12-2下午9:11:57
 */
public class CryptUtils {

    private final static String DES = "DES";

    /**
     * 加密
     * 
     * @param src
     *            数据源
     * @param key
     *            密钥，长度必须是8的倍数
     * @return 返回加密后的数据
     * @throws Exception
     */
    public static byte[] encrypt(byte[] src, byte[] key)
	    throws RuntimeException {
	// DES算法要求有一个可信任的随机数源
	try {
	    SecureRandom sr = new SecureRandom();
	    // 从原始密匙数据创建DESKeySpec对象
	    DESKeySpec dks = new DESKeySpec(key);
	    // 创建一个密匙工厂，然后用它把DESKeySpec转换成
	    // 一个SecretKey对象
	    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
	    SecretKey securekey = keyFactory.generateSecret(dks);
	    // Cipher对象实际完成加密操作
	    Cipher cipher = Cipher.getInstance(DES);
	    // 用密匙初始化Cipher对象
	    cipher.init(Cipher.ENCRYPT_MODE, securekey, sr);
	    // 现在，获取数据并加密
	    // 正式执行加密操作
	    return cipher.doFinal(src);
	} catch (Exception e) {
	    throw new RuntimeException(e);
	}
    }

    /**
     * 解密
     * 
     * @param src
     *            数据源
     * @param key
     *            密钥，长度必须是8的倍数
     * @return 返回解密后的原始数据
     * @throws Exception
     */
    public static byte[] decrypt(byte[] src, byte[] key)
	    throws RuntimeException {
	try {
	    // DES算法要求有一个可信任的随机数源
	    SecureRandom sr = new SecureRandom();
	    // 从原始密匙数据创建一个DESKeySpec对象
	    DESKeySpec dks = new DESKeySpec(key);
	    // 创建一个密匙工厂，然后用它把DESKeySpec对象转换成
	    // 一个SecretKey对象
	    SecretKeyFactory keyFactory = SecretKeyFactory.getInstance(DES);
	    SecretKey securekey = keyFactory.generateSecret(dks);
	    // Cipher对象实际完成解密操作
	    Cipher cipher = Cipher.getInstance(DES);
	    // 用密匙初始化Cipher对象
	    cipher.init(Cipher.DECRYPT_MODE, securekey, sr);
	    // 现在，获取数据并解密
	    // 正式执行解密操作
	    return cipher.doFinal(src);
	} catch (Exception e) {
	    throw new RuntimeException(e);
	}
    }

    /**
     * 数据解密
     * 
     * @param data
     * @param key
     *            密钥
     * @return
     * @throws Exception
     */
    public final static String decrypt(String data, String key) {
	if (data != null)
	    try {
		return new String(decrypt(hex2byte(data.getBytes()),
			key.getBytes()));
	    } catch (Exception e) {
		throw new RuntimeException(e);
	    }
	return null;
    }

    /**
     * 数据加密
     * 
     * @param data
     * @param key
     *            密钥
     * @return
     * @throws Exception
     */
    public final static String encrypt(String data, String key) {
	if (data != null)
	    try {
		return byte2hex(encrypt(data.getBytes(), key.getBytes()));
	    } catch (Exception e) {
		throw new RuntimeException(e);
	    }
	return null;
    }

    /**
     * 二行制转字符串
     * 
     * @param b
     * @return
     */
    private static String byte2hex(byte[] b) {
	StringBuilder hs = new StringBuilder();
	String stmp;
	for (int n = 0; b != null && n < b.length; n++) {
	    stmp = Integer.toHexString(b[n] & 0XFF);
	    if (stmp.length() == 1)
		hs.append('0');
	    hs.append(stmp);
	}
	return hs.toString().toUpperCase();
    }

    private static byte[] hex2byte(byte[] b) {
	if ((b.length % 2) != 0)
	    throw new IllegalArgumentException();
	byte[] b2 = new byte[b.length / 2];
	for (int n = 0; n < b.length; n += 2) {
	    String item = new String(b, n, 2);
	    b2[n / 2] = (byte) Integer.parseInt(item, 16);
	}
	return b2;
    }

}